The present disclosure relates to a rotation force transmission mechanism which rotates a plurality of rotating members by a single driving source and an image forming apparatus including this rotation force transmission mechanism.
In an image forming apparatus, in order to cope with cost reduction, energy saving or space saving, an image forming unit and a sheet conveying unit are configured such that a plurality of rotating members are rotated by employing a single driving source. However, in a case where the single driving source is thus employed, since a rotation direction of each of the rotating members is limited, if the rotation direction of one of the rotating members is switched, the other rotating members need to be stopped, thus causing time loss.
Therefore, in a rotation force transmission mechanism configured to rotate two rotating members by employing a single driving source, a principal construction employs a clutch in order to switch the rotation direction of one rotating member without stopping the other rotating member. In the rotation force transmission mechanism of such a construction, one rotating member is provided with a torque limiter; while at the time in which the clutch is inoperative, a torque applied to the torque limiter is lower than a predetermined set value and then the one rotating member rotates in one direction, if the clutch is operative, a torque applied to the torque limiter is larger than the predetermined value and then the one rotating member is rotated in the other direction.
However, in such a construction, although it is possible to rotate one rotating member in one direction and in the other direction, it is impossible to temporarily stop the rotation of the one rotating member. In a case where the rotation of the one rotating member is stopped, since it is necessary to stop the driving source, the rotation of the other rotating member is also forced to be stopped.
Alternatively, a rotation force transmission mechanism configured to rotate one rotating member by a single driving source is sometimes constructed to have a clutch which stops the rotation of the rotating member in an operative state and permits the rotation of the rotating member in a non-operative state. In such a construction, in the non-operative state of the clutch, a driving force of a driving force is transmitted to the rotating force via a torque limiter and then the rotating member rotates, and in the operative state of the clutch, the rotation of the rotating member is stopped and the transmission of the rotation force from the driving force to the rotating member is interrupted by the torque limiter. In this manner, the rotation of the rotating member can be stopped without stopping the driving source.
However, in such a construction, although the rotation of the rotating member can be stopped without stopping the driving source, it is not possible to switch the rotation direction of the rotating member.